Spinal muscular atrophy (SMA) is a genetic disease that causes muscle weakness and a progressive loss of movement. There is no cure, but therapy and support are available to help manage the condition.
SMA causes the motor neurones in a certain area of the spinal cord to deteriorate. This results in progressive muscle wasting and loss of ability to move parts of the body. See SMA - symptoms for more information.
Motor neurones
Motor neurones are nerve cells that connect the brain and spinal cord to the body’s muscles. The motor neurones send out electrical signals to the muscles, which tell the muscles when to contract (shorten) and relax.
In people with SMA, the motor neurones deteriorate, causing the link between the brain and muscles to break down gradually.
As the link between the brain, spinal cord and muscles breaks down, the muscles that are used for activities such as crawling, walking, sitting up and moving the head are used less and less and become weaker or shrink (atrophy).
Treatment and support
The management of SMA currently focuses on the symptoms and providing supportive care. For example, breathing exercises and support can help to reduce the risk of chest infections, and a feeding tube may be needed for babies that are unable to swallow. See SMA - treatment for more information.
There are also several charities that can provide information and support, such as The SMA Trust and The Jennifer Trust.
How common is SMA?
In the UK, it is estimated that there are between 5,500 and 6,000 people with SMA at any one time.
